Laser Machining System and Method for Machining Three-Dimensional Objects From A Plurality of Directions

ABSTRACT

A laser machining system for machining a work-piece includes a laser scanning head, external optical subsystems, and an image acquisition device. The external optical subsystems correspond to optical channels that include a first optical channel and a second optical channel. The laser scanning head controls an optical path so that a laser beam is directed and focused on the work-piece through the first optical channel and the second optical channel at different times. The first optical channel and the second optical channel correspond to respective specific portions of the work-piece to be machined by the laser beam. The image acquisition device is positioned to view the work-piece through the optical path. The image acquisition device acquires via the first optical channel one or more images of the work-piece to determine a displacement of the work-piece with reference to a best optical focus position of the second optical channel.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/520,089 filed Sep. 24, 2012, which is a national phase ofInternational Application No. PCT/US2010/062498, filed on Dec. 30, 2010,which claims benefit under 35 USC §119(e) to U.S. provisional patentapplication No. 61/291,268, filed Dec. 30, 2009, entitled, “LaserMachining of Cylindrical, Conical or other 3D Objects from DifferentDirections”. The contents of all of these applications are expresslyincorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure are directed generally to lasermachining systems, devices and methods. Some embodiments of thedisclosure are directed specifically to laser machining systems, devicesand methods which can dynamically detect a work-piece position andadjust the laser focus.

BACKGROUND OF THE DISCLOSURE

Ablation is the removal of material from the surface of an object byvaporization, chipping, or other erosive processes. The term “ablation”is often used in the context of laser ablation (i.e., laser machining),a process in which a laser dissolves bonds in a solid or sometimesliquid material. As a result, small fragments of the material in theform of gases, small liquid and/or solid droplets or particles are freedfrom the material and either carried away by a gas stream orre-deposited on a nearby surface.

Common parameters of the ablation process include (i) laser beamwavelength, (ii) laser pulse duration and (iii) laser beam fluence.Laser beam wavelength is an important factor because ablation requiressufficient absorption of the laser light into the material. Absorptionwavelength characteristics are material-specific. Laser pulse durationis also an important parameter, as the mechanisms of ablation can varysubstantially depending on the pulse length. Common pulse regimesinclude ultra-short (10 s of fsec-10 psec), very short (10 psec-1 nsec),short (1-200 nsec), long (1 μsec-1 msec) and continuous-wave (CW). Laserbeam fluence refers to the measure of energy per unit area and isusually measured in J/cm2. The higher the fluence, the more “cuttingability” a laser has. This parameter is particularly important becausethe laser beam fluence must exceed the specific threshold fluence value,F_(th), of the target material for the laser to actually dissolve themolecular bonds and remove material. Laser beam fluence below the F_(th)threshold value will increase a material's temperature, but will notmelt or evaporate it. Threshold fluence values are material-specific,wavelength-specific and pulse duration-specific.

Laser ablation is thus greatly affected by the nature of the materialand its ability to absorb energy, requiring that at the wavelength ofthe laser the material has sufficient absorption to enable ablation. Thedepth over which the laser energy is absorbed, and thus the amount ofmaterial removed by a single laser pulse, depends on the material'soptical properties at the laser wavelength. Laser pulses can vary over avery wide range of durations (milliseconds to femtoseconds) and fluxesand can be precisely controlled.

Thus, laser ablation can be very valuable for both research andindustrial applications. Laser ablation is often employed for precisematerial removal in the fabrication of advanced devices at the scalebetween microns and hundreds of microns and even at the scale ofhundreds of centimeters, e.g., in case of solar panel fabrication. Bothdirect-write and mask-projection techniques are used, and laserwavelength is selected to be compatible with the materials beingprocessed.

Common parameters of the laser drilling process include (i) laserwavelength, (ii) laser pulse energy, (iii) laser pulse duration, (iv)laser pulse repetition rate, (v) the number of laser pulses delivered,(vi) laser spot size and shape as delivered to the work-piece, (vii)laser energy density as delivered to the work-piece and (viii) the pathand velocity of the scanning beam on the work-piece.

In laser machining, attaining high throughput for machining multipleparts corresponds to faster production, but more importantly, lowerproduction cost, resulting in higher profits for a laser-machiningorganization. Thus, any improvement to throughput allows for acompetitive advantage. This is true for either direct-write or maskprojection machining.

Typically, to machine a three-dimensional object, either the object tobe machined must be turned/rotated around one or more axes, the laserbeam must be moved, and/or multiple laser beams must be used. This is sothat all surfaces of the object requiring machining can be lasermachined. In other words, either the work-piece or the output of thelaser machining system must move (or be multiplexed in the case ofmultiple beams) so that all surfaces around the work-piece can receivelaser treatment (e.g., 360 degrees).

In cases when the object to be machined must be turned/rotated aroundone or more axes, even with small objects, current systems utilizemechanical means. Such mechanical means are only capable of effectingthe required movements with required precision and accuracy at limitedspeed, at the rate of approx. 0.3-3 sec per each movement. Often,additional time is required for settling vibrations caused by suchmotion. If the pattern to be machined consists of large number offeatures, the laser ablation process takes only a small fraction of theproduction time as compared to the time required for movement/motion ofthe object for machining for machining one feature at one location toanother feature at another location, resulting in decreased efficiency(e.g., low duty cycle on laser usage). In addition, in situations wherepositioning registration by mechanical means does not provide adequateprecision, other means such as machine vision alignment generally mustbe used. When multiple motions of the object are required, re-alignmentafter each motion adds time to the process cycle and further reduces theefficiency.

On the other hand, a galvanometer scanning approach enables the movementof a laser beam over comparable distances at the rate of 0.001-0.01 secper each move, and times for settling of vibration for the galvanometerscanning head are significantly reduced as compared to the settling ofvibrations due to rotation of the object for machining.

SUMMARY OF THE EMBODIMENTS

Accordingly, systems, devices and methods according to some embodimentsof the present disclosure are provided for laser machining an object(which may also be referred to as a part or a work-piece, such terms maybe used interchangeably throughout the subject disclosure) from aplurality of different orientations. Such objects for machining include,for example, cylindrical shaped objects (e.g., wire, tube, catheter,fibers), as well as other shaped objects.

The systems, devices and methods according to some embodiments of thedisclosure utilize a two-dimensional optical scanner (e.g., galvanometerscanning head) and a laser beam (i.e., a laser). Accordingly, suchembodiments enable the machining of the object from different directionswithout requiring:

-   -   rotation of the object,    -   multiple scanners for each direction,        -   and/or    -   without splitting or multiplexing the laser beam before the        scanner.

To that end, the systems, devices and methods according to someembodiments of the present disclosure enable rapid machining of anobject from different orientations, and may also enable rapid switchingfrom one direction to another with no motion of the object. Suchfunctionality, according to some embodiments, take advantage of the factthat it is easier to quickly control motion of a (relatively) lightscanner mirror, than rotating a relatively heavy fixture associated(e.g., holding, handling) with the object/part being machined.

According to some embodiments, systems, devices and methods of thepresent disclosure can also enable machining a variety of features andshapes into an object, where the size and shape of laser machinedfeatures may be fully programmable (e.g., by software/controller of sucha system).

According to some embodiments, systems, devices and methods of thepresent disclosure can also enable aligning, either manually orautomatically, the laser beam for each orientation of the object.

In some embodiments, the laser may be a diode pumped solid state laser,and moreover, such a laser may include a fourth harmonic module designed(and optimized) to generate 2 W of UV power at 266 nm wavelength and ata repetition rate of 75 kHz (for example). Such a laser can produce avery short pulse width (e.g., less than 20 nanoseconds) and/or high peakpower. The laser, according to some embodiments, may include at leastone of an integrated power meter, high speed shutter and closed loopwater chiller. In some embodiments, the laser can be any laser, pulsedor continuous wave (CW), producing a collimated beam with high enoughenergy and power to machine the object.

In some embodiments, beam delivery can be accomplished by first passinga linearly polarized beam produced by the laser through a quarter-waveplate to convert the beam into a circularly polarized beam to enhancethe cut quality. In some embodiments, such a quarter-wave plate may notbe necessary.

In some embodiments, one or more mirrors can steer/deflect a laser beamto the entrance of a galvanometer scan-head (“scan-head”). Moreover, insome embodiments, systems, methods and devices of the present disclosuremay be equipped with a two-dimensional scan-head. For example, thescan-head in some embodiments can include two (2) mirrors mounted ongalvanometer scanners, which can be controlled via high speedelectronics. Accordingly, the scan-head may be capable of scanning thelaser beam at high speed in a predefined pattern on the object, so as toeffect the predefined pattern (e.g., features) onto/into the object bylaser machining.

In some embodiments, following the scan-head, the laser beam can enter aflat-field (for example) scan lens. The scan lens focuses the laser beamdown to a small spot. For example, a 2 mm diameter input laser beam canresult in a laser beam spot size on a target of approximately 30 μm. Inanother example of some embodiments, the scan-head can have a largefield size of, e.g., 45 mm×45 mm. In some embodiments, the scan-head iswater cooled to achieve stable performance, using, for example, a closedloop water chiller.

In some embodiments, a system for machining a work-piece (e.g, acatheter) may include a scan-head including associated galvanometerscanning mirrors, three (3) small fixed mirrors, spaced approximately120 degrees apart, each for deflecting the laser beam onto an area ofthe catheter corresponding to the 120 degree area with which aparticular mirror is associated. Each small mirror can be used tomachine one hole (as in some embodiments) in each respective area, aplurality of holes, or a particular pattern. In such a configuration(e.g., one hole in each area of the catheter to which a particularmirror corresponds), a single scan-head can sequentially machine allthree holes around the catheter with minimum time between the machiningof each hole. For example, each hole can be machined sequentially in aspiral-like pattern using motion of the scanner, with one of the threemirrors under the scan lens. Similar systems may include more than three(3) mirrors, which results in the spacing between each mirror being less(e.g., four (4) mirrors spaced apart approximately 90 degrees).

In some embodiments, it is not necessary to have all beams placedsymmetrically (either with respect to each other or around thework-piece) and in some embodiments, it is not necessary for each beamto be “folded,” that is, a folded beam arrives onto thework-piece/target via a mirror after exiting the galvanometer head,while a beam which is not folded arrives directly from the galvanometer(though via a field lens) onto the work-piece/target. For example, asshown in FIG. 3C, two beams are “folded” (i.e., via mirrors 312A and312C) and arrive on the work-piece/target from two sides (e.g., 3 and 9o'clock), while the third beam is not folded and arrives vertically ontothe part (e.g., 12 o'clock). One of skill in the art will appreciatethat in some embodiments of the present disclosure, other suchconfigurations may be provided which utilize one or more or no foldedbeams.

One of skill in the art will appreciate that machining is not limited toproducing one or more holes or small openings in/on an object, as anyshaped feature can be machined by programming a controller of thescan-head to machine a particular feature. Such programming may be donevia, e.g., a scanner controller, which may comprise a personal computerand/or microcontroller, and/or the like.

In some embodiments, a single common large field scan lens is used (asnoted above), which focuses the beam for all three orientations (FIG. 1Aor 2A), while in other embodiments, in place of (or in addition to) thelarge-field scan lens, three small-field lenses may be utilized andpositioned before or after a respective mirror (one for each mirror), sothat each lens may address only one beam direction (FIG. 1B or 3A) orarea. In such an embodiment, each small lens is used only to focus thebeam for one hole/pattern orientation. Accordingly, in some embodimentsof the disclosure, each hole or pattern can be laser machined with asingle scan-head and thus the laser beam need not be split ormultiplexed before the scan-head.

In some embodiments, a gas assist nozzle can be mounted in closeproximity to the machining system to supply a gas cooling jet onto theobject during the laser machining process, to maintain machiningquality. In some embodiments, the gas nozzle can be configured toprovide gas flow on the object from a plurality of directions (e.g.,three (3) directions). Moreover, in some embodiments, an exhaust portcan be used to vacuum exhaust the ablation debris out of the machiningsystem.

In some embodiments, a camera and corresponding adapter may be arrangedat the entrance of the scan-head which may comprise a dichroicbeam-splitter (which may be configured to transmit a UV beam and reflectvisible light), a camera lens, and a camera. Such a camera adapter maybe configured to enable observation of the machining of the objectthrough the scan-head assembly. To that end, illuminators can beincluded to illuminate the object for adequate lighting to enableadequate pictures/video for the camera. In some embodiments, upon thescan-head switching an incoming beam from one mirror (e.g., foldingmirror) to another, the camera can observe the processed part from thenew direction at the same time. Accordingly, such embodiments may bepart of a machine vision system to be included with the machining systemto automatically align the scan-head with the object. Such features maybe useful if the mechanical registration of the object with respect tothe scan-head is not sufficient to achieve a required feature/hole/shapelocation with precision. For example, such a machine vision system cancapture an image, digitize it (or the original image may be captureddigitally), then analyze the digital image to automatically measureobject location(s) relative to, for example, known features/positions ofother structure of the system. The information retrieved for such objectlocation(s) from the machine vision can then be used to correct anyscanner offset for each hole/location (i.e., machined pattern). However,in some embodiments, use of the machine vision may impact throughput.

Some embodiments of the disclosure are directed to a laser machiningsystem for machining a work-piece and may include a laser scanning head(e.g., scan-head, or galvanometer scan-head) including at least onefirst mirror to control output/movement of a laser beam, at least onescan-field lens for focusing the laser beam output from the scan head,and a plurality of second mirrors (preferably, in some embodiments, atleast three) each for receiving the laser beam output from the scan lensand reflecting it upon a portion of the exterior of a work-piece formachining, each mirror defining a channel. In some embodiments, the atleast one first mirror comprises two mirrors, together enablingdeflection of the laser over a plane before exiting the scan-head.Moreover, in some embodiments, the at least one scan-field lenscomprises a plurality of scan lenses each for a respective secondmirror.

Some embodiments for a laser machining system according to the presentdisclosure may include one or more of the following:

-   -   a camera for imaging the work-piece or a portion thereof (see,        e.g., machine vision noted above);    -   an illumination source (e.g., LED) for illuminating the        work-piece for imaging by the camera (either direct onto        work-piece or through the scanner);    -   a laser;    -   a controller (e.g., a computer, a micro-processor running        application specific programs to control the laser machining        system) for controlling any one or more components of any of the        embodiments presented in the present disclosure;    -   a quarter-wave plate for converting the laser beam into a        circularly polarized beam;    -   the at least one first mirrors are configured to be moved to        effect movement of the laser along a line (in some embodiments)        or in a plane (in some embodiments).    -   and the like.

In some embodiments, a method for laser machining a work-piece isprovided and comprises at least one of the following steps, andpreferably, several steps, and most preferably, all steps: providing alaser machining system according to any of the noted laser machiningsystems presented by the subject disclosure, positioning a work-piecefor machining in a work-piece retaining area of the machining system,performing a spot laser check along at least one channel of the lasermachining system, acquiring the work-piece location, and machining thework-piece by sequentially utilizing the components of each channel.Such a method may also further include inspecting, automatically, themachining of the work-piece along an area of the work-piececorresponding to at least one channel may be performed for at least onechannel.

In some method embodiments of the present disclosure, spot laserchecking for some laser machining embodiments may comprise deflectingthe scanning head mirror to a corresponding nominal position for a firstchannel, firing a laser beam off the second mirror associated with thefirst channel at a first predetermined location, where the laser beamimpinges upon the work-piece to generate an ablation plume, capturing animage of the plume, locating the plume on the work-piece, comparing thelocation of the plume to the first predetermined location, adjustingcoordinates of the machining system as a result of the comparison, suchthat the first predetermined location corresponds to the location of theplume, and optionally repeating the spot laser check. Such laser spotchecking may be performed for a plurality of channels of the system, oreach channel of the system.

In some method embodiments of the present disclosure, acquiringwork-piece location in some of the machining system embodiments maycomprise deflecting at least one first mirror through a nominal positionfor a respective channel, activating at least one illumination source,imaging the work-piece with a camera to produce a first view of thework-piece for the respective channel, comparing a first stored locationof the work-piece to the actual location of the work-piece from theimage, updating coordinates for the work-piece in the laser machiningsystem based on the comparison and optionally repeating the procedurefor each channel.

In some method embodiments of the present disclosure, inspection of themachined work-piece for some of the laser machining system embodimentsalong a respective channel may comprise: deflecting the at least onefirst mirror of the scanning head to a nominal position relative to therespective channel, activating an illumination source to illuminate aportion of the work-piece corresponding to the area for which machiningis accomplished by the respective channel, acquiring an image of thearea of the work-piece machined along the respective channel, processingthe acquired image to determine at least one of actual dimensions andactual location of machined features relative to the work-piece,determining a difference in at least one of the actual dimensions andactual location and machined features and comparing such to requireddimensions and location of the machine features, and determining whetherthe difference is within a predetermined tolerance, rejecting themachined work-piece if the difference is outside of the predeterminedtolerance, and repeating the inspection procedure for each respectivechannel.

In some method embodiments, the results obtained for any locations,inspections and the like may be logged, and such logging may optionallyinclude associated parameters of the machining selected from the groupconsisting of (for example and not limited to): laser power, number oflaser pulses, and laser pulse rate.

In some embodiments of the present disclosure, a system for lasermachining a work-piece is provided and may include one or more of: alaser scanning head including at least one first mirror to controloutput of a laser beam in at least one direction (e.g., along a line, ina plane), at least one scan-field lens for focusing the laser beamoutput from the scan head, a plurality of second mirrors each forreceiving the laser beam output from the scan lens and reflecting itupon a portion of the exterior of a work-piece for machining, eachmirror defining a channel, a laser for producing a laser beam to enablemachining of the work-piece, positioning means for positioning awork-piece for machining in work-piece retaining area, spot laserchecking means for performing spot laser checks along at least onechannel of the laser machining system, and work-piece locationacquisition means for acquiring an actual location of the work-piece inthe laser machining system. Such system embodiments may also includework-piece inspection means for inspecting the resulting machiningperformed on the work-piece. In some such embodiments, a camera isprovided for capturing at least one image of the work-piece, the cameracomprising at least a portion of one or more of the positioning means,laser spot checking means and work-piece inspection means.

In some embodiments of the present disclosure, a laser machining systemfor machining a work-piece includes a laser scanning head, externaloptical subsystems, and an image acquisition device. The externaloptical subsystems correspond to optical channels that include a firstoptical channel and a second optical channel. The laser scanning headcontrols an optical path so that a laser beam is directed and focused onthe work-piece through the first optical channel and the second opticalchannel at different times. The first optical channel and the secondoptical channel correspond to respective specific portions of thework-piece to be machined by the laser beam. The image acquisitiondevice is positioned to view the work-piece through the optical path.The image acquisition device acquires via the first optical channel oneor more images of the work-piece to determine a displacement of thework-piece with reference to a best optical focus position of the secondoptical channel.

In some embodiments of the present disclosure, the image acquisitiondevice can acquire one or more images via the second optical channel todetermine a location of the work-piece with reference to a best opticalfocus position of the first optical channel. The optical channels caninclude three or more optical channels. The image acquisition device canacquire via one or more of the three or more optical channels one ormore images of the work-piece to determine a location of the work-piecewith reference to a best focus position of another of the three or moreoptical channels.

In some embodiments of the present disclosure, the laser machiningsystem can include an adjustable lens positioned in the optical path anda controller. The controller can compute a displacement of thework-piece with reference to the best optical focus position of thesecond optical channel using the position of the work-piece withreference to the second optical channel and cause adjustment of theadjustable lens to focus the laser beam on the work-piece when the laserbeam is directed to the work-piece via the second optical channel. Thecontroller can compute a displacement of the work-piece with referenceto the best optical focus position of the first optical channel usingthe position of the work-piece with reference to the first opticalchannel and cause adjustment of an adjustable lens to focus the laserbeam on the work-piece when the laser beam is directed to the work-piecevia the first optical channel. The one or more images acquired via thefirst optical channel can be used to determine a lateral displacement ofthe work-piece with reference to the first optical channel. The one ormore images acquired via the second optical channel can be used todetermine a lateral displacement of the work-piece with reference to thesecond optical channel.

The laser machining system can include a scanning mirror positioned inthe optical path and a controller. The controller can compute a lateraldisplacement for the first optical channel using the position of thework-piece with reference to the first optical channel and cause thescanning mirror to adjust the laser beam direction when the laser beamis directed through the first optical channel to compensate for alateral displacement of the work-piece. The controller can compute alateral displacement for the second optical channel using the positionof the work-piece with reference to the second optical channel and causethe scanning mirror to adjust the laser beam direction when the laserbeam is directed through the second optical channel to compensate forthe lateral displacement of the work-piece.

In some embodiments of the present disclosure, the first optical channeland the second optical channel can provide substantially orthogonalviews of the work-piece. The image acquisition device can acquire imagesduring laser machining of the work-piece to dynamically measure, usingimages acquired via the first optical channel, the position of thework-piece with reference to the second optical channel. An illuminationsource can be included for illuminating the work-piece for imaging bythe image acquisition device. A laser and a controller can be included.The controller can control at least one of the scanning head, componentsof the scanning head, image acquisition device, and the laser.

In some embodiments of the present disclosure, the optical subsystemscan each receive separately and at different times the laser beam fromthe laser scanning head, and each of the optical subsystems can includea lens to focus the laser beam.

In some embodiments of the present disclosure, a first image can beacquired of the work-piece by an image acquisition device and via afirst optical channel. The image acquisition device forms part of asystem further comprising a laser scanning head, an adjustable lens, andexternal optical subsystems corresponding to optical channels comprisingthe first optical channel and a second optical channel. The laserscanning head controls an optical path so that a laser beam passes atdifferent times through the first optical channel and the second opticalchannel. The first optical channel and the second optical channelcorrespond to respective specific portions of the work-piece to bemachined by the laser beam. Using the first image of the work-piece, adisplacement of the work-piece with reference to a best optical focusposition of the second optical channel is determined. The adjustablelens is controlled to focus the laser beam on the work-piece when thelaser beam is directed to the work-piece via the second optical channelto compensate for the determined displacement.

In some embodiments of the present disclosure, a second image can beacquired of the work-piece by the image acquisition device via thesecond optical channel. Using the second image of the work-piece, adisplacement of the work-piece with reference to a best optical focusposition of the first optical channel can be determined. The adjustablelens can be controlled to focus the laser beam on the work-piece whenthe laser beam is directed to the work-piece via the first opticalchannel to compensate for the determined displacement.

In some embodiments of the present disclosure, using the first imageacquired via the first optical channel, a lateral displacement of thework-piece with reference to the first optical channel can bedetermined. A scanning mirror can be controlled to adjust the laser beamdirection when the laser beam is directed through the first opticalchannel to compensate for the determined lateral displacement of thework-piece. Using the second image acquired via the second opticalchannel, a lateral displacement of the work-piece with reference to thesecond optical channel can be determined. The scanning mirror can becontrolled to adjust the laser beam direction when the laser beam isdirected through the second optical channel to compensate for thedetermined lateral displacement of the work-piece.

In some embodiments of the present disclosure, the first optical channeland the second optical channel can provide substantially orthogonalviews of the work-piece. Using images acquired via the first opticalchannel and during a period of time of laser machining of thework-piece, the displacement of the work-piece with reference to thebest optical focus position of the second optical channel can bedynamically determined.

In some embodiments of the present disclosure, using an illuminationsource, the work-piece can be illuminated for imaging by the imageacquisition device. The system can include a laser and a controller. Thecontroller can control at least one of the scanning-head, components ofthe scanning-head, the image acquisition device, and the laser. Theexternal optical subsystems can each receive separately and at differenttimes the laser beam from the laser scanning head, and each of theexternal optical subsystems can include a lens to focus the laser beam.

In some embodiments of the present disclosure, a laser machining systemfor machining a work-piece includes a laser scanning head, externaloptical subsystems, and an image acquisition device. The externaloptical subsystems correspond to optical channels including two or moreoptical channels. The laser scanning head controls an optical path sothat a laser beam passes at different times through each of the two ormore optical channels. Each of the two or more optical channelscorresponds to a respective specific portion of the work-piece to bemachined by the laser beam. The image acquisition device is positionedto view the work-piece through the optical path. The image acquisitiondevice acquires via two or more of the two or more optical channels twoor more images of the work-piece to measure a position of the work-piecewith reference to one of the two or more optical channels.

In some embodiments of the present disclosure, a method for lasermachining a work-piece includes acquiring one or more images of thework-piece by an image acquisition device and via each of two or moreoptical channels. The image acquisition device forms part of a systemincluding a laser scanning head, an adjustable lens, and externaloptical subsystems corresponding to optical channels comprising the twoor more optical channels. The laser scanning head controls an opticalpath so that a laser beam passes at different times through each of thetwo or more optical channels. Each of the two or more optical channelscorresponds respectively to specific portions of the work-piece to bemachined by the laser beam. Using the one or more images of thework-piece, a position of the work-piece is determined with reference toone of the two or more optical channels. The adjustable lens iscontrolled to focus the laser beam when the laser beam is directed tothe work-piece via the second optical channel to compensate for thedetermined position.

Further embodiments and objects thereof for the present disclosure willbecome clearer with reference to figures provided with the subjectdisclosure, which include drawings of exemplary embodiments of thedisclosure; a brief description thereof is set out below, as well asreference to the forthcoming detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates a laser machining system for machining an objectfrom multiple directions according to some embodiments of the presentdisclosure.

FIG. 1B illustrates another laser machining system for machining anobject from multiple directions according to some embodiments of thepresent disclosure.

FIG. 2A illustrates a perspective view of a cut-away of a galvanometerscanning head unit for a laser machining system

FIG. 2B illustrates a perspective view of galvanometer scanners includedwithin the galvanometer scanning head unit for effecting movement of thelaser beam, according to some embodiments of the present disclosure.

FIG. 3A illustrates a perspective view of a portion of a laser machiningsystem for machining an object from multiple directions according tosome embodiments of the present disclosure.

FIG. 3B illustrates a partial side, cut-away view of the laser machiningsystem according to FIG. 3, showing internal components of the scan-headand associated structure.

FIG. 3C illustrates a partial exploded perspective view of a lasermachining system according to some embodiments of the presentdisclosure, which utilizes a pair of folded beams, and a single unfoldedbeam, for example.

FIGS. 4A-E represent flow diagrams of various method embodiments of thesubject disclosure, including, for example (and not limited to) a methodfor machining an object from multiple directions according to someembodiments of the present disclosure (e.g., FIG. 4A), where details forthe one or more processes outlined in FIG. 4A can be found in FIGS.4B-4E.

FIG. 5 illustrates a laser machining system for machining an object frommultiple directions and dynamically adjusting a laser beam focusaccording to some embodiments of the present disclosure.

FIG. 6 is a process flow diagram illustrating another example processfor laser machining a work-piece to compensate for the position of thework-piece and using the laser machining system of FIG. 5.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure are directed to systems, devices,and methods for improved laser machining of work-pieces, by directing alaser beam at a work-piece from different directions without requiring aplurality of beams, and without requiring rotation of the work-piece.

In some embodiments, the current subject matter can dynamically detectthe work-piece position for each of several optical channels anddynamically adjust the focus for each of the channels. Detection ofwork-piece position can aid in machining if: (a) the work-piece ismoving or bent, or not consistently positioned in the laser beams;and/or (b) if the laser depth of focus is too shallow to accommodate forthese focus variations.

It is noted that similar structure in different figures is denoted by asimilar reference numeral, with only the first digit of the numberchanging depending upon the figure number (i.e., item 102 in FIGS. 1Aand 1B, correspond to item 202 in FIG. 2A).

Accordingly, in some embodiments, a system for machining a work-piece(e.g., a catheter, cylinder, or other shape or object) is provided andmay include a galvanometer scanning-head unit (as noted earlier,“scan-head”) having at least one mirror (galvanometer scanning mirror)configured to deflect the laser beam (e.g., along a line, or, in aplane), and preferably including two such mirrors, each for deflectingthe laser beam in at least one plane (e.g., X-Y plane). The system mayalso include a plurality of individual secondary mirrors, which arepreferably fixed (though may be foldable), and spaced apart from oneanother, and used to direct the laser beam output from the scan-headonto certain predetermined areas/portions of the work-piece to bemachined (e.g., for a folded beam). For example, in some suchembodiments, three such secondary mirrors are provided and are spacedapart from one another by approximately 120 degrees. Thus, each mirrorcan direct the laser beam output from the scan-head onto one-third (⅓)of the surface area of the work-piece for machining.

FIGS. 1A and 1B are block diagrams which illustrate exemplaryembodiments of such a laser machining system briefly described above. Asshown, exemplary system 100 includes scan-head 102, which includes, forexample, at least one scanning galvanometer mirror, not shown,configured to move a laser beam along in at least one dimension (e.g., aline or in a plane; as noted above, preferably, two such galvanometerscanning mirrors, to enable movement in, for example, an X-Y plane), alaser 104 which produces a laser beam 106 to be received by thescan-head 102 and processed thereby via the mirror(s), an optional firstmirror and/or beam splitter 108 to direct the laser beam (or a portionof the laser beam) into the scan-head 102. Alternatively, the machiningsystem may do away with first mirror/splitter 108 upon the laser beamaxis corresponding directly to the beam entrance 107 to the scan-head.The system may further include a field scan lens 110, a plurality of(i.e., two or more) second mirrors 112 (112A, 112B and 112C) fordirecting the beam emanating from the scan-head 102 onto work-piece 114for machining. The scan-head/galvanometer mirror(s) move todirect/deflect the laser beam from one location to another (and in someembodiments, in rapid fashion) received by the scan-head onto each ofthe plurality of second mirrors 112. Accordingly, each second mirror maybe used to direct the laser beam output from the scan-head onto aspecific portion/area of the work-piece to machine a predeterminedpattern or feature (e.g., a hole) thereon, and thus, enable a singlescan-head to machine the complete surface of the work-piece formachining without movement of the work-piece (for example). Each mirrormay comprise a “channel” for the machining a specific corresponding areaof the work-piece to be machined. In some embodiments, and preferably,multiple channels are provided so that the single scan-head can thensequentially machine features into/onto the entire surface area of thework-piece, at any location around the work-piece, with minimal timebetween each specific portion, by simply directing the laser to eachchannel. Thus, movement of the laser beam by the scan-head may be in aspiral-like pattern, for example, to enable the machining of thework-piece at different locations anywhere around the work-piece usingdifferent second mirrors (e.g., different channels) after the fieldlens.

In some embodiments, as shown in FIG. 1B, such a system may furtherinclude, in addition to or in place of the large field lens 110, aplurality of smaller (e.g., secondary) lenses 116 (116A, 116B, 116C),one each (for example) for the secondary mirrors 112, which may bepositioned either before or after a respective mirror, so that eachlens, according to particular embodiments, may be used to focus the beamin only one direction/channel. In that regard, each smaller lens may beused only to focus the beam for those features to be machined on thework-piece, which corresponds to the portion of the work-piece for whichthe mirror/lens combination is configured to machine. Accordingly, apattern or feature(s) can be laser machined on/into the work-piece usingonly a single scan-head without movement of the work-piece, andmoreover, in some embodiments, the beam need not be split or multiplexedbefore the scan-head (i.e., there is only one laser beam used to machinethe work-piece). Additionally, as shown in FIGS. 1A and 1B, themachining system may also include camera 118 for acquiring images tohelp in work-piece location, laser location, work-piece inspection andthe like (see, e.g., machine vision above).

FIGS. 2A and 2B correspond to illustrations for the scan-head 202 and atleast some of the components thereof, according to some embodiments ofthe present disclosure. As shown, scan-head 202 includes X-planegalvanometer scanning servo 220 for controlling associated galvanometermirror 221, and Y-plane galvanometer scanning servo 222 for controllingassociated galvanometer mirror 223. Deflections of one or another of themirrors 221 and 223 effect movements of laser beam 206 along an X-Yplane 224 (e.g., output laser beam 205A or 205B). Other structure ofscan-head 202 may include controllers 226A, 226B, and 226C, where one oranother of which may be dedicated to a particular galvanometer scanningservo for example, as well as wires/communication lines 228, forreceiving and/or sending at least one of control signals, power, andinformation to and/or from the scan head. The angle of deflection ofincoming laser beam 206 off of mirror 223 may correspond to angle Φ₁,and the angle of deflection off of mirror 221 may correspond to angleΦ₂.

FIGS. 3A, 3B and 3C illustrate embodiments of the present disclosurewhich are similar to those shown in the previous figures, although withslightly more detail. For such a system, as shown, in an effort toprovide a clearer understanding of the elements of the system, amechanical armature surrounding this portion of the system has beenremoved. Machining system 300, according to some embodiments, isprovided which includes one or more, and preferably several or all ofthe following features: a galvanometer scanner head or scan head 302,which includes at least one and preferably two galvanometer mirrors 321,323, focusing lenses 316 (316A for channel A, focusing lens 316B, forchannel B, and focusing lens 316C for channel C). Also included, may bea plurality of mirrors 312 (which may be folding mirrors), where each ofthe mirrors corresponds to a particular area and field lens (i.e., aspecific channel). Specifically, mirror 312A corresponds with lens 316Afor associated channel A, mirror 312B corresponds with lens 316B forassociated channel B and mirror 312C corresponds with lens 316Cassociated with channel C. The scan-head is controlled by acomputer/controller (which may be connected to the scan-head/laser bywired and/or wireless connection) to direct the laser beam over apredetermined portion of a work-piece 314 via mirrors/lenses 312/316(respectively), as well as control on/off, power and duration of thelaser, such that a predetermined feature or pattern is machined on/intoa particular area of the work-piece corresponding to a specificchannel—i.e., at a location anywhere along the circumference of thework-piece.

It is worth noting that FIG. 3C corresponds to some embodiments in whichonly two mirrors 312A and 312C are utilized for creating folded beamsfor those two channels, and no mirror for channel C, effecting anunfolded beam. To that end, and as noted earlier, in some embodiments(e.g., FIG. 3C), it is not necessary to have each beam being “folded;” afolded beam arrives onto the work-piece/target via a mirror arrangedafter beam exits the galvanometer head, while a beam which is not foldedarrives directly from the galvanometer (though via a scan lens) onto thework-piece/target. As shown in FIG. 3C, two beams are “folded” (i.e.,via mirrors 312A and 312C) and arrive on the work-piece/target from twosides (e.g., 3 and 9 o'clock), while the third beam is not folded andarrives vertically onto the part (e.g., 12 o'clock). One of skill in theart will appreciate that in some embodiments of the present disclosure,other such configurations may be provided which utilize one or more orno folded beams.

Laser beam 306 emanating from a laser source (not shown), is directedupon each lens/mirror channel (i.e., A, B, C) by scan-head 302. Thus,the laser beam may be referred to as 305A, 305B and 305C depending uponwhich respective channel it is directed to (i.e., A, B, C). In someembodiments, as indicated above, an illuminating source 330 may beincluded to illuminate the work-piece through the scan-head so that thework-piece may be imaged by camera 318 (still or video). Accordingly,the system illustrated in FIGS. 3A-C may also include one or more LEDs,as illuminating source (though other illuminating sources could beused—any light source familiar to one of skill in the art) to illuminatethe work-piece directly for processing. To that end, in someembodiments, a light source for each channel is provided: LED 320A forchannel A, LED 320B for channel B, and LED 320C for channel C.

In some embodiments, one or more, and preferably a plurality, of processgas nozzles 332 are included. In the embodiments shown in FIGS. 3A-C,the nozzles may surround the work-piece for machining, however, otherlocations may be utilized as long as such nozzles function to disperseand/or remove smoke and/or debris resulting from the machining of thework-piece. To that end, a process gas inlet connector 334 enablesconnection to a source for the process gas nozzles.

The present disclosure presents a plurality of methods for machining awork-piece. In some embodiments, the method comprises a method for lasermachining of a work-piece from a plurality of directions, using one oranother of the embodiments described above, and includes the following.Preliminarily, for example, nominal deflection of thescan-head/galvanometer mirrors is established in order to direct thelaser beam to a nominal location of the pattern to be machined. Inaddition, a relationship is established between systems of coordinatesfor the scan-head controller and a camera (if included). Preparation ofa motion control program(s) operational on the system/PC/controllercontrolling the laser machining system to machine desired features isalso established.

In order to laser machine a work-piece (e.g., a catheter) for someembodiments, for example, one or more, and preferably, several, and mostpreferably, all of the following fabrication steps are carried out. Anexample of such embodiments of an overall method is outlined in the flowdiagram shown in FIG. 4A (particularities of several of the steps notedin FIG. 4A are found with reference to FIGS. 4B-4E). Accordingly, thework-piece is first brought into position at a work-piece area of thesystem (see FIG. 3, ref. numeral 311). Thereafter, laser spot locationchecks (e.g., such as that found in the flow diagram of FIG. 4B) may beperformed on one or more, and preferably each channel of the pluralityof channels (e.g., channels A, B, and C), so that if there is a drift inthe output beam (e.g., its location and/or angular direction), and ifthere are changes in the alignment of the mirrors and another element inthe path delivering the laser beam to at least one of the galvanometermirrors and/or target/work-piece, such a drift(s) require compensation,and thus, in some embodiments, require monitoring. Thus, the system canthen determine if the laser is adequately aimed and/or that thecoordinate system presently being used by the controller is true. Toaccomplish the laser spot location checks, in some embodiments of thepresent disclosure, a scan-head galvanometer mirror(s) (e.g., 321, 323)is deflected to its corresponding nominal position through one of thechannel mirrors, for example, mirror 312A, and then one or more laserpulses is fired. Each pulse may have a duration from femto-seconds tomilliseconds, and if more than one pulse is fired, such pulses canarrive as a burst at the rate from about 1 Hz to about 300 kHz. As aresult of the laser firing, an ablation plume image is captured (eitherduring or immediately after the laser burst). The location of theablation plume is determined and the system updated (e.g., at least oneof the coordinate systems of the camera and scan-head/galvanometerscanning mirrors) with the location of the plume—i.e. the location ofthe laser beam impingement on work-piece for the relative channel.Alternatively, the location of the plume may be compared with an earlierestimated location of the plume (or a feature which is effected onto thesurface of the work-piece by the laser may be compared to such anearlier estimated location), and one or more coordinate systems updatedbased on the actual location of the plume/feature. Thus, in someembodiments, it is determined if the actual location of the laser as itimpinges the surface of the work-piece corresponds to the location thatthe system controller had previously determined the laser to strike. Ifit the location is not correct, the system is updated in at least one ofthe memory and application program of the system so that the laser canbe now accurately aimed at the work-piece for the relevant channel. Thisprocess may be repeated for at least one of the remainder of thechannels (e.g., channels B and C), and in some embodiments, it isrepeated for all remaining channels.

Alternatively, in some cases, instead of monitoring the laser ablationplume, one can monitor the location of the laser mark on the surface ofthe work-piece. The choice between plume and mark is determined by therelative visibility of each, which can be different for differentlasers, spot sizes, laser energies and work-piece materials.

Subsequent to the laser spot location check (according to someembodiments), the work-piece location may be acquired for at least onechannel, and preferably, for each of the plurality of channels (e.g., A,B, and C). An exemplary flowchart for such a process, according to someembodiments, can be found with reference to FIG. 4C. In that regard, andstarting with channel A, for example, the scan-head mirror(s) isdeflected to its nominal position through mirror 312 a. Thereafter, oneor more illuminating sources (e.g., LED(s) 320) are activated so that acamera can image the work-piece/channel to produce view A of thework-piece. Preferably, the image is a digital image. Based on theimage, the work-piece location is determined, by comparing the actuallocation of the work-piece relative to at least one known marker in theimage. Such a marker may be one or another (or several)elements/structure of the system including an element of the camera, forexample, the center of its field of view. Accordingly, an appropriatelocation on the work-piece for the pattern to be machined on thework-piece is determined relative to view A (i.e., relative to channelA) and the scan-head coordinate system is updated based on at least oneof the part location and the plume image (in some embodiments, based onboth). The process may then be repeated for at least one of the otherchannels (B and C), and in some embodiments, preferably both channels.

After at least one of the laser spot location checks and performance ofwork-piece location acquisition, and in some embodiments, preferablyboth are performed, the pattern is sequentially machined into thework-piece, an exemplary process flow for some embodiments can be foundin FIG. 4D. According to some embodiments, the pattern includes specificportions for each channel. Thus, for the three (3) channel systemillustrated in FIGS. 3A-C, the pattern includes pattern portion A forchannel A, pattern portion B for channel B and pattern portion C forchannel C. Thus, for example, pattern portion A is first machined (e.g.,drilled) into the work-piece along channel A (i.e., lens 316A, mirror312A) by deflecting the scan-head mirror(s) to its nominal positionthrough mirror A. The flow of process gas may then be switched on, aswell as a debris removal exhaust vacuum 336. The laser is then switchedon, and is projected onto a portion of the work-piece arranged relativeto channel A (i.e., portion “A” or view A of the work-piece), to producea desired pattern. This portion of the pattern is preferably based onthe updated coordinates for the scan-head determined in the performanceof the steps to acquire part location. Thereafter, the above process forsequential machining is carried out for at least one other channel, andpreferably, in some embodiments, for all channels.

During the machining process, inspection of the machining of thework-piece may be performed for at least one channel, or in someembodiments, for two or more channels, and in some embodiments, allchannels. Such a process, according to some embodiments, is outlined inthe exemplary process flow shown in FIG. 4E. Accordingly, in someembodiments, the following process for in-situ inspection may beperformed for a channel (each/plurality/all). The scan-head mirror(s)are deflected to a nominal position for mirror/channel A (for example).The illumination sources (e.g., one or more LEDs) are activated, so asto illuminate the portion of the work-piece corresponding to the areafor which machining is accomplished for channel A (“portion A”).Thereafter, the camera is activated so as to acquired an image (e.g.,digital image) of portion A, having the portion of the pattern recentlymachined thereon (“view A”). The view A image is then processed, andsuch that the pattern machined thereon is checked for dimensions,location, and the like, with respect to known work-piece features (e.g.,tolerances, and/or comparison to ideal values). This process is thenrepeated for one or more (and preferably all) other channels. Theprocess may be performed by computer/automatically, or may also beperformed by a technician. Depending upon the results of thetolerances/comparison to ideal values, the part is either accepted orrejected. Results of the inspection, and/or rejection of the machinedwork-piece may then be logged, preferably together with other parametersof the system (e.g., laser power, pulse rate, etc.). In someembodiments, the inspection is carried out automatically by the systemthrough computer control (for example) and corresponding applicationprogramming, and the like. It is preferably handled bycomputer/controllers such that the process can occur at a fast rate,rather than inspection by a technician, so that throughput is minimallyaffected. Thereafter, the work-piece with the machined pattern (if allmachining for each channel has been completed and, preferably, alsoinspected), is removed from the system and a new un-machined work-pieceis placed therein—either by a technician or via robotics.

In some aspects, the current subject matter can dynamically detect thework-piece position for one or more optical channels and dynamicallyadjust the focus for each of these channels. Detection of work-pieceposition can aid in machining if: (a) the work-piece is moving or bent,or not consistently positioned in the laser beams; and/or (b) if thelaser depth of focus is too shallow to accommodate for these focusvariations. A camera, galvanometer scanner and multiple lenses andmirrors can be used to view the work-piece from different directions(e.g., along the one or more optical channels). The camera can look ator “view” the work-piece through the same optical path that is traveledby the laser beam through the one or more optical channels. Steering thelaser beam from different directions also enables viewing the work-piecefrom different directions and deducing or determining the location ofthe work-piece in space. Knowledge of work-piece position can enablecontrol of optical components within the optical path of the laser beamto shift the focus and/or direction of the laser beam to the surface ofthe work-piece. The focus can be adjusted for each orientation of thelaser beam around the work-piece. Focusing can be performed using acamera and computer control to capture one or more images, calculate thelocation of the work-piece, and control the optical components, such asa focus actuator and mirrors for directing the laser beam.

FIG. 5 illustrates a laser machining system 400 for machining an objectfrom multiple directions and dynamically adjusting a laser beam focusaccording to some embodiments of the present disclosure. A laser beam406 passes through an adjustable beam expander/collimator 444 having anadjustable lens 444A with a linear actuator allowing adjustable lens444A to move along direction 455. In combination with a fixed lens 444B,this enables adjustment of laser beam divergence and therefore of thefocusing on a work-piece 414. The laser beam 406 passes through adichroic beam-splitter 408, then through a XY laser scanning head 402,such as a galvanometer scanner, which may include at least one scanningmirror 423 to steer the laser beam 406 in one or more directions andthrough the one or more optical channels. In one scanning mirror 423position, the laser beam 406 goes through an optical subsystem thatincludes a focusing lens 416B that focuses the laser beam 406 on thework-piece within an optical channel (e.g., channel B) associated withfocusing lens 416B. In a second scanning mirror 423 position, the laserbeam 406 passes through a second optical subsystem that includes a focuslens 416A that focuses the laser beam 406 on the work-piece 414 withinan optical channel (e.g., channel A) associated with focusing lens 416A,which may include a turning or folding mirror 412A, as shown in FIG. 5,that deflects the laser beam toward and onto the work-piece. An imageacquisition device 418, such as a camera, views the work-piece 414through the same optical path as the laser beam 406, via dichroicmirrors 408 and 448 and a camera lens 424, whether it be along anoptical channel associated with focusing lens 416B or an optical channelassociated with focusing lens 416A.

Laser machining system 400 thus can include one or more opticalchannels, denoted as channel A, channel B, and channel C (although lessthan three or more than three channels are possible), as shown in FIG.5. Laser scanning head 402 can direct the laser beam onto the work piece414 through channels A, B, and/or C at different times allowingdifferent portions of the work-piece to be machined by the laser beam.In an implementation, channels A and B can provide substantiallyorthogonal views of the work-piece 414, although other configurationsand non-orthogonal views are contemplated.

Illumination is possible through several modalities, for example, viacommon upstream illuminator 430 illuminating via the shared optical pathand/or via light-emitting diode (LED) illuminators 460A, 460B, and/or460C located proximal work-piece 414. The laser's wavelength cantypically be at a different spectral region than the light used toilluminate the work-piece 414 (e.g., LEDs 460 A, B, C and/or commonupstream illuminator 430).

Work-piece 414 can have an ideal position (e.g., an origin) formachining. However, due to work-piece 414 moving, bending, or notconsistently being positioned in the ideal position, system 400 canacquire images and determine a position displacement of the work-piece414 as viewed through one or more optical channels. Displacement of thework-piece as viewed through the one or more optical channels can be oneor both of depth displacement (e.g., too near or too far) and/or lateraldisplacement (e.g., too left or too right), also sometimes referred toas offsets and shifts, respectively. The ideal depth for a given channelcan also be referred to as the best optical focus position of a givenchannel. In some embodiments system 400 can compensate for lateraldisplacement of the work-piece 414 by controlling laser scanning head402, including the one or more scanning mirrors 423 and/or one or morefolding mirrors (412A and/or 412C as shown in FIG. 5). In someembodiments system 400 can compensate for depth displacement of a givenchannel by controlling the adjustable lens 444A.

Depth displacement of the work-piece 414 as viewed through a givenoptical channel can be determined by acquiring images through adifferent optical channel. For example, the image acquisition device 418can be positioned to view the work-piece 414 through optical channel Aassociated with focusing lens 416A as shown in FIG. 5. The imageacquisition device 418 can acquire via optical channel A one or moreimages of the work-piece 414 that depict the work-piece 414 as being toohigh or too low in the view, which in turn indicates a depthdisplacement of the work-piece 414 with reference to the best opticalfocus position of channel B as being either too near or too far,respectively, from the best optical focus position. In other words,channel A is utilized to determine the distance of the work-piece 414along channel B's depth axis (or, referring to an alternative frame ofreference, channel A is utilized to determine the distance of thework-piece from the focusing lens 416B of channel B) to calculatewhether the laser beam is converging appropriately on the work-piece414, i.e., the work-piece 414 is at the best optical focus position ofthe laser beam 406, or the work-piece 414 is in front of or behind thebest optical focus position of the laser beam 406. In someimplementations, determination of depth displacement for channel B canbe performed by, using the acquired images from channel A and imageprocessing and/or machine vision techniques, computing a distance withinthe image between the work-piece 414 and the best optical focus positionfor channel B. The best optical focus position for channel B as viewedthrough channel A may be predetermined, predefined, and/or determinedduring a calibration procedure.

To determine a depth displacement for channel A, one or more images canbe acquired using channel B. In some implementations, determination ofdepth displacement for channel A can be performed using the acquiredimages from channel B and by computing a distance within the imagebetween an origin (e.g., zero) position and a current position of thework-piece 414 (i.e., to the left or the right of the origin). Likewise,in the example arrangement of FIG. 5, a depth displacement for channel Ccan be determined by acquiring images using channel B. Other methods ofdetermining the depth displacement using the acquired images arepossible.

Lateral, or side-to-side displacement of the work-piece 414 within agiven channel can be determined by acquiring images through that samechannel. For example, the image acquisition device 418 can acquireimages through channel A to determine a lateral displacement of thework-piece 414 with respect to a best lateral position of channel A.Likewise, image acquisition device 418 can acquire images throughchannel B to determine a lateral displacement of the work-piece 414 withrespect to a best lateral position of channel B. Similar images can beacquired to determine lateral displacement with respect to channel C. Insome implementations, determination of a lateral displacement forchannel A can be performed using the acquired images from channel A andimage processing and/or machine vision techniques and by computing adistance within the image between the work-piece 414 and the bestlateral position (e.g., the ideal position or work-piece 414 origin) forchannel A. Likewise, lateral displacement can be computed for each ofchannels B and C using images acquired via channels B and C,respectively.

The system 400 of FIG. 5 can include a controller 465 to compute thedepth and/or lateral displacement of the work-piece 414 in one or moreof channels A, B, and/or C. Controller 465 can also cause adjustment ofthe adjustable lens 444A to focus the laser beam 406 on the work-piece414 when the laser beam 406 is directed to the work-piece 414 via theoptical channels A, B, and/or C. Adjustment of adjustable lens 444A canbe based on the determined depth displacement for a given channel.Controller 465 can also cause scanning mirrors 423 and/or foldingmirrors 412A and 412B to adjust to direct the laser beam 406 to thework-piece 414 based on the determined lateral displacement.

Controller 465 can also control other components of the system 400, suchas the scanning-head 402, components of the scanning-head 402, imageacquisition device 418, and laser 406.

In some implementations, image acquisition device 418 can acquire imagesthrough one or more of the optical channels during laser machining ofthe work-piece 414 to dynamically measure, using the acquired images,the position of the work-piece 414 (including the lateral and depthdisplacements). In some implementations, system 400 can compensate forthe position of the work-piece 414 during laser machining of thework-piece 414.

In operation and according to an example implementation, laser scanninghead 402 steers the view of the image acquisition device 418 to observework-piece 414 from the direction of focus lens 416B (e.g., throughoptical channel B). The depth-wise positioning of the work-piece 414along the optical channel A can be measured by acquiring one or moreimages along optical channel B, determining whether the work-piece 414is off-center from an identified origin or zero point with respect tooptical channel B, and thereafter calculating that off-center distance,which in turn equates to the depth displacement of the work-piece 414along optical channel A. The focus of the laser beam along the opticalchannel A can be corrected by adjustable lens 444A based on the imageacquisition device 418 images acquired from direction of lens 416B(e.g., through optical channel B) and the determined displacement.

Next, laser scanning head 402 steers the view of image acquisitiondevice 418 to observe the work-piece 414 from the direction of lens 416Aand folding mirror 412A (e.g., through optical channel A). Thedepth-wise positioning of the work-piece 414 along the optical channel Bcan be measured by acquiring one or more images along optical channel A,determining whether the work-piece is off-center (e.g., above or below)an identified origin or zero point with respect to optical channel A andthereafter calculating that off-center distance, which in turn equatesto the depth displacement of the work-piece 414 along optical channel B.The focus of the laser beam along the optical channel B can be correctedby adjustable lens 444A based on the image acquisition device 418 imagesacquired from direction of lens 416A (e.g., through optical channel A)and the determined displacement.

Laser scanning head 402 may also steer the view of the image acquisitiondevice 418 to the work-piece 414 from the direction of lens 416B (e.g.,through optical channel B) for purposes of determining the lateral beamposition with respect to optical channel Band correcting the same byappropriate tilt of scanning mirrors 423 based on the measurement of theposition of the work-piece 414 from an origin or zero point. Similarly,laser scanning head 402 may also steer the view of the image acquisitiondevice 418 to the work-piece 414 from the direction of lens 416A andfolding 412A (e.g., through optical channel A) for purposes ofdetermining the lateral beam position with respect to optical channel Aand correcting the same by appropriate tilt of scanning mirrors 423based on the measurement of the position of the work-piece 414 from anorigin or zero point.

Using the current subject matter, both the lateral displacement of thework-piece 414 (across the impinging beam) and its axial or depthdisplacement (along the beam's direction) can be determined andcompensated for to maintain the laser beam 406 centered on work-piece414 and in focus.

FIG. 6 is a process flow diagram illustrating another example process600 for laser machining a work-piece to compensate for the position ofthe work-piece and using the laser machining system 400 of FIG. 5. At610, an image of the work-piece 414 can be acquired by image acquisitiondevice 418 via one of the optical channels (channel A, B, or C). At 620,a displacement of the work-piece from a best optical focus position of adifferent channel can be determined using the acquired image of thework-piece 414.

At 630, adjustable lens 444A can be controlled to focus the laser beam406 when the laser beam 406 is directed to the work-piece 414 via thecorresponding optical channel to compensate for the determineddisplacement. The current subject matter can be performed as acalibration procedure (e.g., before machining a work-piece) ordynamically during machining of the work-piece (e.g., to compensate forany shifts or displacements that may occur during the machiningprocess).

Various embodiments of the subject matter described herein may berealized in digital electronic circuitry, integrated circuitry,specially designed ASICs (application specific integrated circuits),computer hardware, firmware, software, and/or combinations thereof.These various embodiments may include embodiment in one or more computerprograms that are executable and/or interpretable on a programmablesystem including at least one programmable processor, which may bespecial or general purpose, coupled to receive data and instructionsfrom, and to transmit data and instructions to, a storage system, atleast one input device, and at least one output device. In particular,some embodiments include specific “modules” which may be implemented asdigital electronic circuitry, integrated circuitry, specially designedASICs (application specific integrated circuits), computer hardware,firmware, software, and/or combinations thereof.

These computer programs (also known as programs, software, softwareapplications or code) include machine instructions for a programmableprocessor, and may be implemented in a high-level procedural and/orobject-oriented programming language, and/or in assembly/machinelanguage. As used herein, the term “machine-readable medium” refers toany computer program product, apparatus and/or device (e.g., magneticdiscs, optical disks, memory, Programmable Logic Devices (PLDs)) used toprovide machine instructions and/or data to a programmable processor,including a machine-readable medium that receives machine instructionsas a machine-readable signal. The term “machine-readable signal” refersto any signal used to provide machine instructions and/or data to aprogrammable processor.

Some or all of the subject matter described herein may be implemented ina computing system that includes a back-end component (e.g., as a dataserver), or that includes a middleware component (e.g., an applicationserver), or that includes a front-end component (e.g., a client computerhaving a graphical user interface or a Web browser through which a usermay interact with an embodiment of the subject matter described herein),or any combination of such back-end, middleware, or front-endcomponents. The components of the system may be interconnected by anyform or medium of digital data communication (e.g., a communicationnetwork). Examples of communication networks include a local areanetwork (“LAN”), a wide area network (“WAN”), and the Internet.

The computing system may include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

Any and all references to publications or other documents, including butnot limited to, patents, patent applications, articles, web-pages,books, etc., presented in the present application, are hereinincorporated by reference in their entirety.

Although a few variations have been described in detail above, othermodifications are possible. For example, the logic flows depicted in theaccompanying figures and described herein do not require the particularorder shown, or sequential order, to achieve desirable results.

Although particular embodiments have been disclosed herein in detail,this has been done by way of example for purposes of illustration only,and is not intended to be limiting with respect to the scope of theappended claims, which follow. In particular, it is contemplated thatvarious substitutions, alterations, and modifications may be madewithout departing from the spirit and scope of the invention as definedby the exemplary claims. Other aspects, advantages, and modificationsare considered to be within the scope of the following exemplary claims.The exemplary claims presented are representative of only some of theembodiments and features disclosed herein. Other unclaimed embodiments,inventions, and features are also contemplated.

What is claimed is:
 1. A laser machining system for machining awork-piece, the system comprising: a laser scanning head; externaloptical subsystems corresponding to optical channels comprising a firstoptical channel and a second optical channel, the laser scanning headcontrolling an optical path so that a laser beam is directed and focusedon the work-piece through the first optical channel and the secondoptical channel at different times, the first optical channel and thesecond optical channel corresponding to respective specific portions ofthe work-piece to be machined by the laser beam; and an imageacquisition device positioned to view the work-piece through the opticalpath, the image acquisition device acquiring via the first opticalchannel one or more images of the work-piece to determine a displacementof the work-piece with reference to a best optical focus position of thesecond optical channel.
 2. The laser machining system of claim 1,wherein the image acquisition device acquires one or more images via thesecond optical channel to determine a displacement of the work-piecewith reference to a best optical focus position of the first opticalchannel.
 3. The laser machining system of claim 2, wherein the opticalchannels comprise three or more optical channels and wherein the imageacquisition device acquires via one or more of the three or more opticalchannels one or more images of the work-piece to determine adisplacement of the work-piece with reference to a best focus positionof another of the three or more optical channels.
 4. The laser machiningsystem of claim 1, further comprising: an adjustable lens positioned inthe optical path; and a controller to compute a displacement of thework-piece with reference to the best optical focus position of thesecond optical channel using the position of the work-piece withreference to the second optical channel and cause adjustment of theadjustable lens to focus the laser beam on the work-piece when the laserbeam is directed to the work-piece via the second optical channel. 5.The laser machining system of claim 2, further comprising: a controllerto compute a displacement of the work-piece with reference to the bestoptical focus position of the first optical channel using the positionof the work-piece with reference to the first optical channel and causesadjustment of an adjustable lens to focus the laser beam on thework-piece when the laser beam is directed to the work-piece via thefirst optical channel.
 6. The laser machining system of claim 2, whereinthe one or more images acquired via the first optical channel are usedto determine a lateral displacement of the work-piece with reference tothe first optical channel, and the one or more images acquired via thesecond optical channel are used to determine a lateral displacement ofthe work-piece with reference to the second optical channel.
 7. Thelaser machining system of claim 6 further comprising: a scanning mirrorpositioned in the optical path; and a controller to compute a lateraldisplacement for the first optical channel using the position of thework-piece with reference to the first optical channel and cause thescanning mirror to adjust the laser beam direction when the laser beamis directed through the first optical channel to compensate for alateral displacement of the work-piece, the controller to compute alateral displacement for the second optical channel using the positionof the work-piece with reference to the second optical channel and causethe scanning mirror to adjust the laser beam direction when the laserbeam is directed through the second optical channel to compensate forthe lateral displacement of the work-piece.
 8. The laser machiningsystem of claim 1, wherein the first optical channel and the secondoptical channel provide substantially orthogonal views of thework-piece.
 9. The laser machining system of claim 1, wherein the imageacquisition device acquires images during laser machining of thework-piece to dynamically measure, using images acquired via the firstoptical channel, the position of the work-piece with reference to thesecond optical channel.
 10. The laser machining system according toclaim 1, further comprising an illumination source for illuminating thework-piece for imaging by the image acquisition device.
 11. The lasermachining system according to claim 1, further comprising a laser and acontroller, wherein the controller controls at least one of thescanning-head, components of the scanning-head, image acquisitiondevice, and the laser.
 12. The laser machining system according to claim1, wherein the optical subsystems each receive separately and atdifferent times the laser beam from the laser scanning head, and each ofthe optical subsystems includes a lens to focus the laser beam.
 13. Amethod for laser machining a work-piece, the method comprising:acquiring a first image of the work-piece by an image acquisition deviceand via a first optical channel, the image acquisition device formingpart of a system further comprising a laser scanning head, an adjustablelens, and external optical subsystems corresponding to optical channelscomprising the first optical channel and a second optical channel, thelaser scanning head controlling an optical path so that a laser beampasses at different times through the first optical channel and thesecond optical channel, the first optical channel and the second opticalchannel corresponding to respective specific portions of the work-pieceto be machined by the laser beam; determining, using the first image ofthe work-piece, a displacement of the work-piece with reference to abest optical focus position of the second optical channel; andcontrolling the adjustable lens to focus the laser beam when the laserbeam is directed to the work-piece via the second optical channel tocompensate for the determined displacement.
 14. The method of claim 13,further comprising: acquiring a second image of the work-piece by theimage acquisition device via the second optical channel; determining,using the second image of the work-piece, a displacement of thework-piece with reference to a best optical focus position of the firstoptical channel; and controlling the adjustable lens to focus the laserbeam when the laser beam is directed to the work-piece via the firstoptical channel to compensate for the determined displacement.
 15. Themethod of claim 14, further comprising: determining, using the firstimage acquired via the first optical channel, a lateral displacement ofthe work-piece with reference to the first optical channel; andcontrolling a scanning mirror to adjust the laser beam direction whenthe laser beam is directed through the first optical channel tocompensate for the determined lateral displacement the work-piece. 16.The method of claim 15, further comprising: determining, using thesecond image acquired via the second optical channel, a lateraldisplacement of the work-piece with reference to the second opticalchannel; and controlling the scanning mirror to adjust the laser beamdirection when the laser beam is directed through the second opticalchannel to compensate for the determined lateral displacement of thework-piece.
 17. The method of claim 13, wherein the first opticalchannel and the second optical channel provide substantially orthogonalviews of the work-piece.
 18. The method of claim 13, further comprising:dynamically determining, using images acquired via the first opticalchannel and during a period of time of laser machining of thework-piece, the displacement of the work-piece with reference to thebest optical focus position of the second optical channel.
 19. Themethod of claim 13, further comprising illuminating, using anillumination source, the work-piece for imaging by the image acquisitiondevice.
 20. The method of claim 13, the system further comprising alaser and a controller, wherein the controller controls at least one ofthe scanning-head, components of the scanning-head, the imageacquisition device, and the laser.
 21. The method of claim 13, whereinthe external optical subsystems each receive separately and at differenttimes the laser beam from the laser scanning head, and each of theexternal optical subsystems includes a lens to focus the laser beam. 22.A laser machining system for machining a work-piece, the systemcomprising: a laser scanning head; external optical subsystemscorresponding to optical channels comprising two or more opticalchannels, the laser scanning head controlling an optical path so that alaser beam passes at different times through each of the two or moreoptical channels, each of the two or more optical channels correspondingto a respective specific portion of the work-piece to be machined by thelaser beam; and an image acquisition device positioned to view thework-piece through the optical path, the image acquisition deviceacquiring via two or more of the two or more optical channels two ormore images of the work-piece to measure a position of the work-piecewith reference to one of the two or more optical channels.
 23. The lasermachining system of claim 22, wherein the optical channels comprisethree or more optical channels and wherein the image acquisition deviceacquires via two or more of the three or more optical channels two ormore images of the work-piece to determine a displacement of thework-piece with reference to a best focus position of another of thethree or more optical channels.
 24. The laser machining system of claim22, further comprising: an adjustable lens positioned in the opticalpath; and a controller to compute the position of the work-piece withreference to a best optical focus position using the position of thework-piece with reference to the one of the two or more optical channelsand cause adjustment of the adjustable lens to focus the laser beam onthe work-piece when the laser beam is directed to the work-piece via theone of the two or more optical channels.
 25. The laser machining systemof claim 22, wherein the one or more images acquired via the firstoptical channel are used to determine a lateral displacement of thework-piece with reference to the first optical channel, and the one ormore images acquired via the second optical channel are used todetermine a lateral displacement of the work-piece with reference to thesecond optical channel.
 26. The laser machining system of claim 25further comprising: a scanning mirror positioned in the optical path;and a controller to compute a lateral displacement for one of the two ormore optical channels using the position of the work-piece withreference to one of the two or more optical channels optical channel andcause the scanning mirror to adjust the laser beam direction when thelaser beam is directed through one of the two or more optical channelsto compensate for a lateral displacement of the work-piece.
 27. Thelaser machining system of claim 22, wherein two of the two or moreoptical channels provide substantially orthogonal views of thework-piece.
 28. The laser machining system of claim 22, wherein theimage acquisition device acquires images during laser machining of thework-piece to dynamically measure, using images acquired via the one ofthe two or more optical channels, the position of the work-piece withreference to one of the two or more optical channels.
 29. The lasermachining system according to claim 22, further comprising anillumination source for illuminating the work-piece for imaging by theimage acquisition device.
 30. The laser machining system according toclaim 22, further comprising a laser and a controller, wherein thecontroller controls at least one of the scanning-head, components of thescanning-head, image acquisition device, and the laser.
 31. The lasermachining system according to claim 22, wherein the optical subsystemseach receive separately and at different times the laser beam from thelaser scanning head, and each of the optical subsystems includes a lensto focus the laser beam.
 32. A method for laser machining a work-piece,the method comprising: acquiring one or more images of the work-piece byan image acquisition device and via each of two or more opticalchannels, the image acquisition device forming part of a system furthercomprising a laser scanning head, an adjustable lens, and externaloptical subsystems corresponding to optical channels comprising the twoor more optical channels, the laser scanning head controlling an opticalpath so that a laser beam passes at different times through each of thetwo or more optical channels, each of the two or more optical channelscorresponding respectively to specific portions of the work-piece to bemachined by the laser beam; determining, using the one or more images ofthe work-piece, a position of the work-piece with reference to one ofthe two or more optical channels; and controlling the adjustable lens tofocus the laser beam when the laser beam is directed to the work-piecevia the second optical channel to compensate for the determinedposition.
 33. The method of claim 32, further comprising: determining,using the second image of the work-piece, a displacement of thework-piece with reference to a best optical focus position of one of thetwo or more optical channels; and controlling the adjustable lens tofocus the laser beam when the laser beam is directed to the work-piecevia one of the two or more optical channels to compensate for thedetermined displacement.
 34. The method of claim 33, further comprising:determining, using the one or more images acquired via the two or moreoptical channels, a lateral displacement of the work-piece withreference to one of the two or more optical channels; and controlling ascanning mirror to adjust the laser beam direction when the laser beamis directed through one of the two or more optical channels tocompensate for the determined lateral displacement the work-piece. 35.The method of claim 32, wherein the two of the two or more opticalchannels provide substantially orthogonal views of the work-piece. 36.The method of claim 32, further comprising: dynamically determining,using images acquired via the two or more optical channels and during aperiod of time of laser machining of the work-piece, the displacement ofthe work-piece with reference to the best optical focus position of oneof the two or more optical channels.
 37. The method of claim 32, furthercomprising illuminating, using an illumination source, the work-piecefor imaging by the image acquisition device.
 38. The method of claim 32,the system further comprising a laser and a controller, wherein thecontroller controls at least one of the scanning-head, components of thescanning-head, the image acquisition device, and the laser.
 39. Themethod of claim 32, wherein the external optical subsystems each receiveseparately and at different times the laser beam from the laser scanninghead, and each of the external optical subsystems includes a lens tofocus the laser beam.